The concept of opportunity cost, that is, the maximum value of other optional things that are given up in order to obtain something. To put it more simply, if the optional interval is ABCD, the values decrease in turn, the opportunity cost of choosing A is B, and the opportunity of choosing non-A is A. ..

According to this definition, other benefits given up due to excessive reserves are opportunity costs. Excessive export is the cause of excessive foreign exchange reserves, not its opportunity cost; B imported inflation caused by foreign exchange is a side effect of excessive foreign exchange, which is the main part of international reserves. Gold, ordinary drawing rights and special drawing rights are subordinate, so B is the answer; Similar to A, export volume is the result, and international reserves are the result. Too much and too little exports affect the total foreign exchange reserves, not the result of the total foreign exchange reserves. This is practically impossible. For example, if country A holds a large amount of foreign exchange in country B, and country B experiences deflation, that is, country B's currency is getting more and more valuable, and it can buy more goods, then on the one hand, Congress A will pursue the goods of country B to a greater extent, on the other hand, country B will also reduce its imports from country A, so it is far less difficult to control the so-called imported deflation than imported inflation, so D is wrong.